1. Field of the Invention
The present invention relates to a semiconductor integrated circuit device having a multilevel interconnection structure. More specifically, the invention relates to design rules to form interconnections and via contacts of a multilevel interconnection that is made of copper or materials containing copper as the principal ingredient. The present invention is applied to, for example, a complementary insulated gate semiconductor integrated circuit (CMOS LSI).
2. Description of the Related Art
Instead of conventionally-used aluminum, copper has been used as an interconnection material of LSI having a multilevel interconnection structure in order to decrease the resistance of an interconnection and a via contact and improve the reliability of the LSI.
However, when an interconnection or a via contact made of copper is in a specific shape, it has been turned out that a contact failure occurs due to stress migration caused in the manufacturing process of LSI to decrease the reliability of the LSI.
It has turned out that a contact failure occurs frequently especially in a CMOS LSI so configured that a lower interconnection having a great width is electrically connected to an upper interconnection through a single via contact.
In a semiconductor integrated circuit device so configured that a lower interconnection having a great width is electrically connected to an upper interconnection through a via contact as described above, it is desirable to prevent a contact failure from occurring to improve the reliability of the semiconductor integrated circuit device.
According to one aspect of the present invention, there is provided a semiconductor integrated circuit device comprises a first interconnection which is made of materials containing copper as a principal ingredient and has a given width, length, thickness and volume, a second interconnection which is made of materials containing copper as a principal ingredient and provided above the first interconnection, and at least one via contact which is made of materials containing copper as a principal ingredient and through which the first interconnection and the second interconnection are electrically connected to each other, the at least one via contact including one via contact which is provided when one of the width and the volume of the first interconnection is not larger than a given value and a plurality of via contacts, which are arranged at regular intervals, each of which is not larger than a given value, in a predetermined region of the first interconnection, when one of the width and the volume of the first interconnection exceeds a given value.